Organic acids in coffee in relation to the degree of roast
The organic acids in hot water extracts of various coffee in relation to the degree of roast were studied by a combination of partition chromatography on silica gel and paper chromatography. Rf values of several phenolic acids are given. The following acids were found to be present in green as well as in roasted coffee: Acetic, propionic, butyric, valeric, malic, citric, quinic, caffeic, chlorogenic, isochlorogenic, neochlorogenic, a further isomer of chlorogenic, p-coumaryl quinic and two isomers of ferulyl quinic. Formic acid was found only in roasted coffee. The predominant acids, in coffee were chlorogenic and citric. Caffeic and quinic acids were present only in traces. During roasting the amounts of formic and acetic acids increased. Between 32 and 52 of the chlorogenic acid was destroyed during roasting, whereas the loss in citric acid was 33 to 56 and for malic acid the loss was 16 to 40, depending on the particular coffee and the final roast temperature. This simultaneous formation and decomposition of organic acids during roasting of coffee explains why the pH of coffee brews reaches a minimum with a light roasted coffee
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| Format: | biblioteca |
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| Subjects: | COFFEA, FRUTO, TOSTADO, COMPOSICION, ACIDOS ORGANICOS, PROCESAMIENTO, PERGAMINO, |
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